Large portions of hydrocarbon location and production activities involve drilling, pumping, and conduit installation beneath the earth's surface. Drilling, pumping, and conduit installation operations may include water location and distribution. Drilling, pumping, and conduit installation operations may also include sewage processing and distribution, or support installation of electrical power lines or telecommunications transmission lines. Drilling, pumping, and conduit installation activities often use lengths of pipes, which may be joined together in a variety of different manners. There are several considerations associated with joining pipes. For example, drilling activities may require torque to be transmitted across numerous pipes. Thus a joint may need to be strong enough to transmit torque and resist failure.
Additionally, some industry standards exist related to pipe section diameters. For example, internal pipe diameters are often standardized so expected flow and capacity of the drill string can be achieved. Standards also exist concerning pipe outer diameters that dictate clearances between the outer pipe surface and a wellbore casing, for example. Thus there are often limits on material sizes and thicknesses that can be used for drill pipe segments.
Currently, pipe segments are joined with threaded connections. Although a threaded connection will adequately join pipe segments, a threaded connection does not transfer torque effectively while rotating both to the left and to the right. That is, threads may loosen or disengage when the pipe segments are rotated in a direction opposite the direction used to tighten to pipe segments together. Some have addressed this issue by adding teeth to the ends of threaded joint sections. Teeth may be capable of transferring torque interconnected pipe segments, even if the pipe segments are rotated in a direction counter the tightening direction. But teeth are often ineffective and result in a weakened joint.
Drill pipe segments of the prior art are often made of steel alloy, such as 4140 steel or other steel alloys. As one of ordinary skill in the art will appreciate, such pipe segments are heavy and difficult to manage. As described in U.S. Pat. No. 3,126,214 to Wong, previous attempts to reduce drill pipe weight entailed providing an aluminum drill pipe with stainless steel joints adapted to interconnect two or more drill pipe segments together. For example, FIG. 1 shows interconnected drill pipe segment of the prior art comprising a male joint section 1 and a female joint section 2. The male joint section 1 and the female joint section 2 are connected to the aluminum drill pipe section 4 via threads provided on each of the male and female joint sections and the aluminum pipe section 4. In the example shown, the aluminum pipe section 4 possesses outer threads 6 and the male and female joint section includes internal threads 5. The outer diameter 8 of the drill pipe section 4 is larger than the internal diameter 7 of the male and female joint sections. Thus, to interconnect the male and female joint sections to the aluminum drill pipe section, the joint sections must be heated to approximately 650° F., which expands the joint sections so they can be threadingly received on the aluminum drill pipe section. After the threaded connections are engaged, the male and female joint sections are allowed to cool, or forcibly cooled by water spray, which bonds the joint sections to the aluminum pipe section.
One of ordinary skill in the art will appreciate that one drawback of the current method of joining stainless steel joint sections 2 and aluminum drill pipe section is that premature joint section cooling will prevent complete integration of the joint section to the pipe section. If the interconnection of joint section to pipe section is not ideal, the joint section cannot simply be removed by re-heating, as the heat required for joint section expansion will adversely affect the aluminum drill pipe section.
It is appreciated that one may postulate that further weight reductions can be achieved if both the drill pipe section and the joint sections are made of aluminum. The use of an aluminum drill pipe with threaded end interconnections as found in the prior art would weaken the drill string because under the conditions normally experienced in drilling operations, the threads of interconnected aluminum drill pipe joint segments would adhere and gall. Galling may lead to catastrophic failure. Further, even if an anti-galling coating is used, aluminum threads are weak and, thus, are not ideal to transfer torque.
Those of ordinary skill in the art will also appreciate that because steel joints are the widest portion of the drill pipe segment and, thus, the drill string; they often contact cement and casing walls or the stone wellbore. Abrasive contact between joint sections and the wellbore tends to wear the joint sections. Accordingly, hard bands are often integrated into the steel joint sections before they are connected to the aluminum pipe section. Hard bands are designed as a sacrificial surface that bears the brunt of the frictional interaction between the drill string and the wellbore. Thus the joint members must be re-banded from time to time which is done by removing the existing band and welding a new band onto the joint section. The excess heat required by this process will degrade the interconnected aluminum pipe.
Accordingly, a need exists for a method and apparatus, which takes into account one or more of the issues discussed above as well as possibly other issues.